The iPad is a unique workspace for editing photos. It takes the tactile immediacy of something like a Cintiq tablet and unshackles it from a desktop editing environment.
You can directly manipulate items on screen, make precise adjustments with the Apple Pencil, and do it all from the comfort of your couch, the seat of an airplane on the way to your next shoot, or wherever life takes you.
iOS 11 brought some really great improvements to iOS, and specifically to the iPad. This guide from Marius Masalar (@mostlymarius) on the Sweet Setup on what works, what doesn't, and how he does it, is a great resource.